Holding relay with permanent magnet



May 2, 1950 L. H. MATTHIAS ETAL HOLDING RELAY WITH PERMANENT MAGNET 3Sheets-Sheet 1 Filed May 28, 1945 INVENTOR-S IUTOP/Vf).

y 2, 1950 L. H. MATTHIAS ETAL 2,505,904

HOLDING RELAY WITH PERMANENT MAGNET Filed May 28, 1945 3 Sheets-$heet 2ATTOR/VE X y 1950 L. H. MATTHIAS ET AL HOLDING RELAY wrm PERMANENTMAGNET 3 Sheets-Sheet 3 Filed May 28, 1945 Q FUN llll HH Q g 4 F m I l Mm KQYR IN V EN TORS /mm BY ATTOPl/[X I Patented May 1950 I UNITED 'STA-T Es, jPATiEIN T o1=1= cE-} HOLDING RELAY wrrn PERMANENT MAGNET LynnH. Matthias, Fox Point, and Karl K. Stong, Whitefish Bay, Win, assignorsto Allen-Bradley Company, Milwaukee, Wis., a corporation of.

/ Wisconsin 1 Application May 28, 1945, Serial No. 596,360

This invention relates to electromagnetic attracting and holdingapparatus dependent upon permanent magnetism for the holding actionthereof; The invention resides more specifically in an improved formofapparatuses of this type in which a permanently magnetizablecore'portion is so disposed, intermediate the ends of a magnetizingcoil, as to be subjectedv as nearly as possible to the full magnetizingforce of which 7 result, excessive pounding and wear of mechanical aswell as electrical parts has been encountered. I

A furtherdisadvantage of magnets heretofore planet-5 there indicated;-and Fig." 6 is a diagram of one form of circuit which -a Claims. (01. 1-341) of the relay shown in Fig. I viewed through the maybe employedwith the apparatus shown in the preceding figures.

.Referring now to the drawings the magnet of this invention is thereshown associated with parts adapted to form an electric relay, for whichuse the magnet is particularly well adapted. As appears more clearly inFigs. 4 and 5 a magnet frame I of rectangular "U-shaped iorm is securedby rivets to a mounting bracket 2, thus forming not only a magnet framebut also a supporting framework for the entire rclay The upp r ends ofthe upwardly facing prongs of the U-shaped frame I are provided withbent back ears 3 to provide means for firmattachment through screws 4with a top frame plateii. In this way a recavailable has been 'thetendency thereof to close i when unduly low'voltage is applied and thenon termination of such deficient voltage to drop open again instead ofremaining latched. Through the use of the apparatus of this inventionthe shortcomings of magnets of thistype previously tangular, opensldedmagnet frame is formed composed of magnetic material ofcomparatively high magnetic permeability and low retentivity.

Permanently secured in a centrally disposed hole in the upper plate 5 isa downwardly ex-* tending upper core member 6 held in place by a peenedrim l. The upper core member 5 is composed of magnetic material of highpermeability andlow retentivity and is provided with an accuratelymachined lower face 8. Disposed beneath and spaced from the upper coremember '6 is a lower core members formed oi! similar material; the upperface ill of which is also acknown is overcome. The magnet of thisinvention iseasily permanently magnetized by a magnetizing force notmaterially greater than that appropriate for pick up and closing. Inthis way v undue pounding and wear may be avoided. Furthermore, anyapplied voltage sufficient to cause pick up and closing also is adequateto establish sufilcient permanent magnetism to insure the retaining ofthe magnet in closed position. y This invention is herein described byreference I to the accompanying drawings forming a part hereof and inwhichthere is set forth by way of illustration and not of] limitationoneform in which the apparatu of th s invention may be embodied.Inthedrawings:

Fig. 1 is a side view in elevationof' a relay embodying amagnetconstructed inaccordance with thisinvention;

Fig. 2 is a-top planivlew or the relay shown in' Fig. "1 with the uppercontact cover removed to expose the contacts; r

Fig. 3 is a bottom plan view of the relay shown in Fig. 1 with thebottom contact cover removed; Fig. 4 is a side elevation in section ofthe relay shown in Fig. 1' viewed through the plane 4-4 indicated in Fig2; v 1'18. 5 is a Iront view in elevation and in section tentivity andcoercive force.

curately machined. Disposed between and'in intimate engagement wlththefaces 8 and i0 and there rigidly held bythe tubular rivet i I leanintermediate core member 12.

The intermediate core member i2 is composed of a magnetic material ofexceptionally high readapted for the construction of the intermediatecore member l2 are the alloys of iron, aluminum and nickel orcobalt ofthe general class commonly called Alnicof However, any materialexhibiting the property of retaining permanent I magnetism to a highdegree may be employed and for this reason a successful practicing ofthis invention is not dependent upon the selection of the particularalloy or alloys above mentioned for the intermediate core member I2.

The parts above described constitute the entire stationary frame of themagnet and with these parts a coil i3 is associated in a particularmanner so as to produce the specific magnetizing action required. As maybe observed in Figs. 4 and 5 the coil "surrounds the upper and lowercoremembers 6' and 9 and notionly surrounds the intermediate core memberl2 but extends a very substantial distance beyond the same both aboveand below it. By reason of this construction the flux created upon theenergization of coil i3 is.

Particularly well g r at or in the nearvlcinity ofthe eye of the coilI3. Coil I3 may comprise if desired two separate windings as is setforth in Fig. 6, in which winding I3ais a closing or magnetizing windingand lib is an opening or demagnetization winding which creates a flux oropposite polarity to that of winding I3a.

- Immediately below the core member 9 a large I circular opening it isformed in the lower hori- Disposed zontal part of the frame member I. tomove to and from the positions shown in Figs. 4 and 5, within theopening I, is a collar shaped armature I5 having a vertical sleeveportion l6 and a seating rim I7. As appears in Fig. 4 the seating rim I1is arranged to come into sealing engagement with the bottom face offrame memher I while a small air gap is retained between the upper endof the sleeve l6 and the lower face of the lower core member 9. l

Armature I5 is mounted upon and guided in its movement by a non-magneticguide rod I8, received with a close but nevertheless freely sliding fitwithin the bore of tubular rivet I i. To

form an engaging seat between the armature l5 and the rod l8 a boss I9,riveted in place within the armature I5 as shown, is bored to be closelyreceived upon the reduced diameter portion 20 of the rod I8. Thearmature I5 isheld in place against. a shoulder on rod it formed by areduced diameter portion 20 by means of a preloaded spring. ZIinterposed between the armature I5 and a lower insulating'movablecontactcarrier 22 held in place by a C washer 23 which engages a groovein theend of rod I8. To aug v ment the opening force due to gravity andto render the magnet operative in inverted position an openingcompression spring 25 received within the recesses in lower core member9 and armature l5 and interposed between these two place by screws 71.Mounted upon contact support 27 is a pair of closed-position stationaryload contacts and terminals 28 and an oppositely disposed pair ofopen-position stationary load contacts and terminals 29. Also mountedupon the contact support 2] is a pair of stationary closedposition pilotcontacts and terminals 3@ as well as a pair of open-position pilotcontacts and terminals 3 i Mounted upon the upper end of the actuatingrod l8 and there held between a c washer 32.

en ing a groove in the upper end of rod it, and a spring 33 engaging ashoulder 38, is an insulating movable contact carrier 35. The movablecontact carrier 35 is so disposed as to carry movable bridging contacts35 and 8? between load contacts 28 and 29 and to carry bridging contactsl8 and 39 to and from pilot contacts 30 and II. Secured to posts 40 andM by means of sleeve .nuts 42 and 43 is an upper contact cover 4 3.

Mounted on the lower face of frame member I by means of brackets 45 andscrews 46 is a lower stationary contact support 4'! composed ofinsulating material. Carried by the support 47! are stationary loadcontacts and terminals 48 and 49 in position to be engaged by movablebridging contacts 50 and II carried upon movable insulating contactcarrier 22. Stationary cross connecting contacts 52 serve to complete aload circuit from tel 48 to terminal when the switch is in closedposition. A lower contact cover 53 positioned as shown is held in placeby sleeve nuts 54 and 55 which engage threaded supporting posts it and51! which in turn are secured to the contact support il by riveting.

Binding posts 58, 59, 50, Si, 52 and 63 serve to provide connection withthe windings 13a and I327 of coil l3 and the pilot contacts 86 and 3!and with a control circuit as shown in Fig. 6 for energization of themagnet to cause the same to close and open.

As shown in Fig. 6 direct current supply main 6% of positive polarity isconnected by lead 88 with a normally open start push button bl which isjoined by a lead B8 with terminal 59 and one of the two stationary pilotcontacts 33. Movable pilot contact 38 which is normally closed engagesthe other stationary pilot contact at which is joined through lead 69and terminal 58 with closing winding Mia. The opposite end of closingwinding Isa isjoined through terminal til and lead it with the negativepower main 55. Winding I3a is of appropriate resistance and number ofturns to cause closing of the magnet and permanent magnetizationthereof;

For opening main is joined by lead ll normally open stop push button 12,lead 73, terminal 62, contacts 3i and wand lead it with terminal Bl atone end of winding 63b. The opposite end of winding 83b is joinedthrough terminal 53 andlead i5 with positive power main 66. With themagnet in closed position, closure of stop button 12 completes a circuitfor the creation of reverse flux in winding l3!) of a reduced magnitudelimited by resistance it which may be either a distributed internalresistance in the winding I3b or an external resistance as shown. Suchlimited reverse flux serves to demagnetize the hard core portion 62 tocause the magnet to open. Numerous forms of such circuits ma be employedto accomplish the result desiredv including circuits which have but asingle winding in coil I3 with external resistance arranged to beintroduced when reverse polarity opening current is applied.

Upon excitation of coil ii for closing, the flux prevailing the magneticcircuit begins to build up but movement of ature is does not take placeinitially because of substantial leakage of flux from the lower face ofcore member 9 to the lower horizontal portion of frame I without pass;ing through the armature it. As flux further increases, a substantiallylarger portion thereof begins to pass from the lower face of core mennber t to the armature l5 and thence to the frame 9. When the flux pamingthrough the armature 55 reaches a value suficient to create anattractive force capable of overcoming the action of spring 26 and otherresistingjorces, the armature i5 starts to move. By the time suchmovement starts to take place flux has been built up to a verysubstantial value, sumcient to establish considerable permanentmagnetism in the intermediate core member 82. As movement of armature l5progresses, the leakage of fiui: directly from thelower face of coremember 9' to frame 9, is very rapidly diminished, until substantiallyall of the flux passes through the a raeoam During the closing actiontheflux in the mag could pass from the core member to the frame member Ior to the upper plate without passing through the part to be permanentlymagneticed. This action would be further encouraged by the fact'thatalloys suitable for permanent magnet use do not have thehighest possiblepermeability. By reason of the relationship of the parts ,of theapparatus of this invention a certain definite minimum excitation ofcoil 13 is necessary to cause pick up of thearmature. Any excitationexceeding such minimum will cause the armature ii to close and closepositively and at the same time will insure the magnetization ofintermediate core member I2, sufflciently to insure the retention of themagnet in closed position.

' It is not necessary to excite the coil I 3 to any degree in excess ofthat necessary to cause the picking up of armature IS in order to createthe necessary permanent magnetism to retain the magnet in closedposition and therefore the magnet ofthis invention may be operatedwithout unnecessary mechanical wear and tearand with the full assurancethat closing will be positive and reliable.

We claim as'our invention:

1. In an electrically controlled permanent magnet the combinationcomprising a central magnetic 'core having a relatively short medialportion composed of permanently magnetizable material exhibiting highcoercive force and high retentivity and relatively longer end portionsof magnetic material of high permeability disposed on opposite sides ofsaid medial portion and in contact therewith, said short medial portionextending entirely across and completely separating said end portions;windings surrounding said core and extending lengthwise thereof beyondsaid medial portion on both sides thereof; a magnetic frame membersurrounding said core and said windings having a magnetic top end platesecured to the top end of said core, apair of magnetic side legs securedto said top end plate extending downwardly outside of said windings,

' magnet the combination comprising a central magnetic core havingiarelatively short medial portion composed of permanently magnetizablematerial exhibiting high coercive force and high retentivity andrelatively longer end portions of magnetic material of high permeabilitydisposed on opposite sides of said media1 portion and in contacttherewith, said short medial portion extending entirely across andcompletely separating said end portions; windings surrounding said coreand extending lengthwise thereof beyond said medial portion on bothsides thereof; a mag- .netic frame member secured to and extendinglaterally from the top end of said core 'and downwardly outside of saidwindings terminating in' a lower end plate transversely positioned withrespect to said core andextending across the free end of said core apredetermined distance beneath the free end of said core; said lower endplate being provided with an aperture disposed opposite the free end ofsaid core; a movable armature having a shank portion freely movablewithin said aperture having a length approximating the spacing betweenthe free end of said core and said lower end plate, the lower end ofsaid armature being provided with a flangeadapted to abut the lowermargins'of the aperture in said lower end plate when said armature is inclosed position with the upper end of the shank portion of said armaturein close proximity to the free end of said core; guiding means for saidarmature adapted to guide the same for free movement withinthe aperturein said lower end plate; stop, means positioned to maintain saidarmature when in open position at a level such that the upper end of theshank portion of I said armature is approximately flush with said lowerend plate to provide a leakage path for a substantial proportion of theflux which threads said core directly between the lower end of said.0016 and said lower end plate without passage through said armaturewhen said armature is in open position, and opening means adapted tourge said armature to open position.

3.111 an electrically controlled permanent magnet the combinationcomprising "a central magnetic core having a relatively short medialportion composed of permanently magnetizable and a magnetic lower endplate secured to said t core, spaced from and extending across the freeI end of said core; said lower end plate being procontact the lowersurface of said endplate ad-.-

iacent to said aperture when said armature is in closed position; and anopening spring disposed side legs in perpendicular relationship to'saidlmaterial exhibitinghigh coercive force and high retentivity andrelatively longer end portions of magnetic material of highpermeability'disposed on opposite sides'of said medial portion and incontact-therewith, said short medial portion extending entirely acrossand completely separating said end portions; windings surrounding saidcore and extending lengthwise thereof beyond said medial portion on bothsides thereof; a

magnetic frame member secured to andextending laterally from the top endof said'core and downwardly outside of said windings terminating-in alower endv plate transversely positioned with respectto said core andextending across the free end of said core a predetermined distancebeneath the'free end of said coreysaid lower end plate being providedwith an aperture disposed opposite the free end of said core;

- a movable armature having a shank portion free- 1 1y movable withinsaid aperture having a length v approximating the spacing between thefree end between said armature and core adapted'to urge said armature toopen position, 2. In an electrically controlled permanent of said coreand said lower end plate, the lower end of said armature being providedwith a flange adapted to abut the lower margins of .the aperture in saidlower end plate when'said armature is in closed position with the upperend of the shank portion of said armature in -close proximity to thefree end of said core;" av guidin: rod

tor-said armature extending axially through said core adapted to guidesaid armature for tree plate; stop means positioned to maintain saidmovement within the aperture in said lower end 4 and-said-iower endplate without passage through said armature when said armature is anopen sition; an opening means adapted to urge said armature to openposition.

aooam The 'foli owinkfreifrences are of record in the Number mamas #:wsums PA Date Name Gheney -Z. July 14, 3968' Warren Jami. 1918 Lane Aug.39,1921

' Brown Apr. 12, 1

Ray Nov. 2, 193'? Stahel Dec. 21, 1937 Kelley Mar. 21, 1939 Perry Aug.22, 1939 Van i lamenburg et a1. a. Oct. 1?, was

